1. Technical Field
The present invention relates to a production method of a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode, a piezoelectric element, a liquid ejecting head, and a liquid ejecting apparatus.
2. Related Art
As a piezoelectric element used in a liquid ejecting head, for example, there is a piezoelectric element configured by interposing a piezoelectric material that presents an electromechanical conversion function between two electrodes. Such a piezoelectric element is mounted in the liquid ejecting head as, for example, an actuator device in a flexural vibration mode. As a representative example of the liquid ejecting head, for example, there is an ink jet type recording head in which a part of a pressure generation chamber communicating with a nozzle opening that discharges ink droplets is configured as a vibration plate, and the vibration plate is deformed by the piezoelectric element to pressurize ink in the pressure generation chamber, thereby discharging the ink as ink droplets from the nozzle opening.
As one of such kinds of ink jet type recording head, there is an ink jet type recording head in which piezoelectric elements having insulating films made of zirconium oxide, first electrodes, piezoelectric layers, and second electrodes are arranged on one surface side of a flow path formation substrate having pressure generation chambers formed therein. Here, as the piezoelectric layer, a layer using a material containing lead, zirconium, and titanium, such as, lead zirconate titanate (PZT) is widely used.
However, when the piezoelectric layer (PZT) is formed as a film on the insulating film made of zirconium oxide, the piezoelectric layer is formed into a crystal having a grain size of greater than 1 μm, so that there is a problem in that the piezoelectric layer is more likely to become a starting point of breakage when a voltage is applied to the piezoelectric element.
Therefore, a method of suppressing an increase in grain size of a piezoelectric layer by providing titanium on an insulating film is suggested (for example, refer to JP-A-2002-314163).
In JP-A-2002-314163, after a first electrode is formed on the entire surface of an insulating film, titanium that becomes a nucleus is formed on the first electrode, a first piezoelectric film is then formed, and thereafter the first electrode and the first piezoelectric film are patterned. In addition, titanium that becomes a nucleus is further provided over the insulating film and the first piezoelectric film, and a second or further piezoelectric films are formed on the titanium.
However, even in a case where titanium is provided as in JP-A-2002-314163, there are problems in that small holes occur in a boundary part between the first electrode and the insulating film, and when a voltage is applied to a piezoelectric element, cracks occur in the piezoelectric layer from the small holes as the starting points.
This problem occurs not only in the ink jet type recording head but also in heads that eject liquids other than ink. This problem is not limited to piezoelectric elements mounted in the liquid ejecting heads and is also present in piezoelectric elements mounted in other devices.